Ahead of today's second practice session, the air temperature is 30.7 degrees C, while the track temperature is 53.6 degrees. It remains bright and sunny.
As a reminder of the updates this weekend, Mercedes has a new front wing endplate and front brake cooling, while Red Bull has updated it steering and front brakes cooling.
McLaren has similarly updated its rear brake cooling, steering, cooling louvres and mirror stay while Alpine and AlphaTauri have only upgraded their steering.
Williams has updated its steering and front brake cooling, while Haas has updated its steering.
No changes to the Ferrari, Aston Martin or Alfa Romeo.
Both Bottas & Schumacher suffered MGU-K issues in FP1, the German also suffering a damaged driveshaft. Haas will put the healthy MGU-K from PU 2 to PU1 for FP2, and switch it back again to PU2 for FP3 tomorrow.
Meanwhile, Bottas will have to use a 3rd MGU-K for the rest of the Monaco weekend after his first power unit was completely lost after the failure in FP2 at Barcelona. He was already running PU2 this morning when the MGU-K failed.
Confused? You are not alone.
Leclerc was quickest earlier, edging out Perez and Sainz, and when we say 'edging out', we refer to the fact that the three were covered by just 0.070s.
Only a few drivers used the softs earlier, certainly none of the front runners, but even so all were pushing hard from the outset. While the only red flag was down to Schumacher stopping at the pitlane entrance, there was much use of the various escape roads.
An unwelcome return was that of porpoising, with Mercedes =once again heavily impacted, though a number of other teams suffered, including Ferrari, Williams and Alpine.
The lights go green and Albon leads the way, followed by Latifi, Magnussen and Ocon, all are on mediums.
Verstappen and Perez are also out early.
Albon gets things underway with an 18.066.
Soon there are 17 drivers on track, nearly all sporting mediums, as Leclerc (hards) goes quickest (15.762), ahead of Magnussen, Perez, Hamilton and Alonso.
No sooner has Norris posted a 14.970 than Verstappen responds with a 14.915.
Sainz posts a 14.880, but is quickly demoted when Perez stops the clock at 14.001.
"Vibration is very bad, very bad," says Tsunoda, "I can't drive."
Nine minutes in and Bottas heads out, leaving Ricciardo and Zhou as the only no shows.
Hamilton improves to fourth (14.713), but is instantly leapfrogged by his Mercedes teammate with a 14.634.
That said, Norris demotes the pair of them when he crosses the line at 14.623.
Ricciardo heads out on mediums.
Vettel does brilliants not to hit the wall at the Swimming Pool as the rear of his car gets very loose.
Gasly goes fourth with a 14.361, only to be demoted by Russell (14.327).
The session is red-flagged when Ricciardo goes into the barriers at the Swimming Pool exit.
"Daniel, is the car OK?" he is asked. "I'm OK," he replies.
Replay shows him losing the rear of the car, after suffering understeer at the start of the complex, in Tabac, on what was his first flying lap of the afternoon.
The left-front section of the car is badly damaged.
The session resumes with 37 minutes remaining. Bottas leads the way, followed by Zhou, Ocon, Gasly and Latifi. All are on softs.
"There is still debris on the braking line," complains Latifi.
As more drivers head out, all bar Gasly, Bottas, Zhou and Norris are porting the red-banded rubber.
Perez raises the bar with a 13.324 as Alonso goes third (13.912).
Despite being quickest in S1, Hamilton can only manage sixth overall (14.267), as Perez complains that he's lost his left mirror.
A 13.884 sees Russell go third.
Quickest in the final sector only, Leclerc goes quickest with a 13.125.
Meanwhile, Bottas, Hamilton and Stroll are the latest to miss the apex at the Nouveau Chicane.
On-board shows Ocon really struggling with the Alpine, unlike his teammate who is currently fifth.
"Everyone just come on, pleeease," urges Tsunoda as he seeks out some clear air.
A 13.103 sees Verstappen go top, but Leclerc is already looking set to improve. Indeed he does, crossing the line at 12.764.
Sainz makes it a Ferrari 1-2 with a 13.066.
Having gone quickest in S1, Hamilton is totally mystified as to where he lost time over the rest of the lap.
Norris improves to fourth with a 13.294, ahead of Perez, Russell, Alonso, Vettel, Magnussen and Hamilton.
A big lock up sees Hamilton head down the infamous escape road at the hairpin where Nico Rosberg did his famous reversing trick back in the day.
Norris has a close encounter with the barriers at Ste Devote. "I hit the wall at Turn 1," he admits, "pretty hard." However, he is able to make it back to the pits.
"I've hit the wall at Turn 12, front-right," reports Russell, as Sainz makes it a Ferrari 1-2 with a 12.877.
Leclerc was all set to improve again when he encounters a very, very slow Latifi hogging the racing line in the final sector.
Having finally fitted the softs, the Alfa pair are still at the wrong end of the timesheets, with Bottas 18th and Zhou 16th.
The Finn subsequently improves to 13th with a 14.468.
"I don't think I damaged anything," says Perez after another brush with the barriers, "but have a check."
"What the **** is this guy doing, never looking in his ******* mirrors. Always, **** always," says Gasly, though we're not sure who he's talking about. Answers on a postcard please.
With 15 minutes remaining, attention turns to Sunday afternoon and the high fuel runs. While most are on softs, a few are on mediums.
"Graining front and rear," warns Ocon.
Norris makes full use of the escape road at Ste Devote after overshooting it.
More profanities from Gasly though it isn't clear why.
"Let us have more detail on the drivability," Russell is asked. "No power!" is the terse response.
Though he's currently 12th, it's noticeable that Hamilton has not been complaining about bouncing so much this afternoon.
The session ends. Leclerc is quickest, ahead of Sainz, Perez, Verstappen, Norris Russell, Gasly, Alonso, Vettel and Tsunoda.
Magnussen is eleventh, ahead of Hamilton, Bottas, Albon, Zhou, Stroll, Schumacher, Ocon, Latifi and Ricciardo.
Check out our Friday gallery from Monaco, here.